Base station equipment for mobile communication

ABSTRACT

In a base station apparatus in a mobile communication comprising a transmitting/receiving section for each sector, a baseband processing section for each sector and a sector switch to select a connection with the transmitting/receiving section and the baseband processing section, when a handover is made, a soft handover is executed by selecting a plurality of sectors on the basis of information concerning peripheral sectors obtained from a mobile station and connecting the transmitting/receiving sections of the selected sectors and the baseband processing section with the sector switch.

TECHNICAL FIELD

The present invention relates to a base station apparatus in a mobilecommunication in which transmission and reception are executed bysector, preferably to a base station apparatus in a mobile communicationto reduce the scale of the hardware of a base station and improve thecommunication quality.

BACKGROUND ART

As a mobile communication technique in a cellar system, a sectortransmission and reception method, in which a base station has aplurality of base station antennas composed of directive antennas andeach of a plurality of cells comprises a plurality of sectors where adifferent frequency is used for each sector to communicate, has beendeveloped.

The sector transmission and reception method allows to use the samefrequency repeatedly in nearer cells, which makes the efficiency offrequency reuse higher and increases the number of users accommodated.

In the sector transmission and reception method described above, when amobile station in communication moves from a cell to another cell, ahandover between cells by a switching equipment is executed. And when amobile station cross a boundary between sectors, a handover betweensectors by controlling of a base station is executed.

For instance, In Japanese Unexamined Patent publication No.7-131845, abase station apparatus for executing sector-transmitting-receiving isdescribed. The base station apparatus is to execute data communicationon the basis of CDMA (Code Division Multiple Access) mobilecommunication system. Illustrated in FIG. 6, the base station apparatusdescribed above comprises M numbers (M is an integer number indicatingthe number of cells) of sector antenna 303, M numbers of batchmodulating/demodulating section 302-1 through 302-M to modulate anddemodulate transmission and reception signals by a plurality ofcommunication channels in the batch in a frequency determined for eachsector and N numbers (N is an integer number indicating the numbers ofcommunication channels) of baseband signal processing section 301-1though 301-N to process baseband signals of each communication channel.In addition, in FIG. 6, CLK illustrates a clock signal to operate eachcircuit.

As illustrated in FIG. 7, each of baseband signal processing section301-1 through 301-N comprises transmission signal processing section 201to generate transmission signal Sn corresponding to a modulation methodfrom transmission data SDn, transmission signal selecting circuit 202 tooutput this transmission data Sn to the instructed sector, receptionsignal selecting circuit 204 to select signal RAm(m=1˜M) received byeach sector according to an instruction, reception signal selectingprocessing section 203 to detect reception data RDn corresponding to thecommunication channel from selected reception signal Rn, monitor signalselecting circuit 206 to select signal Am received at each sectoraccording to an instruction to output, reception quality monitoringsection 205 to monitor the reception quality of the reception signalselected by monitor signal selecting circuit 206, and control section207 to instruct monitor signal selecting circuit 206 to switch a sectorto be selected at a certain time intervals, and to instruct transmissionsignal selecting circuit 202 and reception signal selecting circuit 204to select a sector having the most appreciate reception quality on thebasis of the detection result by reception quality monitoring section205.

In the base station transmitting and receiving apparatus, transmissiondata SDn (n=1˜N) of the number n channel is input to transmission signalprocessing section 201 at the number n of baseband signal processingsection 301-n. Transmission signal processing section 201 generatestransmission signal Sn corresponding to a modulation method from thistransmission data SDn. This transmission signal Sn is input intotransmission signal selecting circuit 202. Transmission signal selectingcircuit 202 outputs this transmission signal Sn [Sn,m=Sn(m=SEL1),Sn,m=0(m≠SEL1)] to a sector instructed by selecting signal SEL1 fromcontrol section 207. In addition, Sn is a waveform indicated in digitalsignals.

Transmission signal Sn,m output from transmission signal selectingsection 202 of signal processing section 301-n is input to batchmodulating/demodulating section 302-1 through 302-M. Batchmodulating/demodulating section 302-m add transmission signal from S1,mto SN,m provided respectively from baseband signal processing sectionfrom 301-1 to 301-N, converts them into analog signals, then convertsinto transmission radio signals. This transmission radio signals aretransmitted from antenna 303 at a sector. Signal RFm (m-1˜M) indicatestransmission and reception radio signals of the number m sector.

On the other hand, signals received by antenna 303 of each sector isinput into batch modulating/demodulating section 302-1 through 302-M.Batch modulating/demodulating section 302-m converts reception radiosignals in a band corresponding to N numbers of communication channelsinto baseband signals collectively then converts them into digitalsignals to output. This baseband signal RAm is provided to all ofbaseband signal processing section 301-1 through 301-N.

Reception signal selecting circuit 204 at baseband signal processingsection 301-n selects reception signal Rn [Rn=RAm(m=SEL1)] of the sectorinstructed by selecting signal SEL1 at control section 207 from Mnumbers of reception signals RA1 through RAM to output into receptionsignal processing section 203. Reception signal processing section 203detects reception data RDn corresponding to the communication channelfrom the selected reception signal Rn.

And, control section 207 switches selecting signal SEL2 for monitorsignal selecting circuit 206 at intervals of predetermined durationtime. Monitor signal selecting circuit 206 receives it, selectsreception signal RQn [RQn=RAm (m=SEL2)] of the sector instructed byselecting signal SEL2 from M numbers of reception signals from RA1 toRAM to output into reception quality monitoring section 205. Receptionquality monitoring section 205 monitors the reception quality of theselected reception signal RQn (for instance, reception power,interference wave power, examination error power, error ratio andothers) to transmit to control section 207 with reception quality signalQn. As described above, control section 207 monitors the receptionquality of each sector by using reception quality monitoring section 205and outputs selecting signal SELL to select the sector having the bestreception quality into transmission signal selecting circuit 202 andreception signal selecting circuit 204.

Accordingly, when a mobile station moves crossing a sector, the mostappropriate sector is selected automatically within baseband signalprocessing section 301-1 through 301-N.

As described above, in a conventional base station apparatus in a mobilecommunication, when a mobile station moves crossing a sector, a handovercontrolled by the base station, where the base station decides the mostappropriate sector on the basis of reception signals received from amobile station, is executed.

And, since a handover in a conventional base station apparatus iscontrolled by the base station where a basebnad processing sectionselects the sector having the best reception quality on the basis ofreception quality signals from each sector, there has been a problemthat a scale of hardware becomes larger because a comparing circuit isnecessary to detect the reception quality from each sector and select asector on the basis of the detected qualities.

And, since a handover is executed by a hard handover in which aconnection with a cannel is once terminated to switch a channel for anew connection with another channel, there has been a problem thatgenerated short break brings deterioration in reception quality.

And, since a transmission from a base station is executed through oneline, there has been a problem that a soft handover, in which receptionsignals from a plurality of sectors are composed for handover, can notbe executed.

DISCLOSURE OF INVENTION

The present invention aims to solve the problems described above and hasan object to provide a base station apparatus in a mobile communicationcapable of excellent quality communication with the expansion ofhardware scale in a base station reduced and the flexibility andreliability of the system improved (in which the expansion of hardwarescale in a base station is reduced, the flexibility and reliability ofthe system are improved, which makes excellent quality communicationpossible).

Hence, in the present invention, in a base station apparatus in a mobilecommunication comprising a plurality of transmission/receiving sectionseach for each sector, a plurality of baseband processing sections eachfor each sector and a sector switch to select a connection between atransmission/receiving section and a baseband processing section, when ahandover is made, a soft handover between sectors is executed byselecting a plurality of sectors on the basis of information ofperipheral sectors obtained from a mobile station and connectingtransmission/receiving sections and baseband processing sections of theselected sectors with a sector switch.

According to the present invention, a soft handover between sectors isexecuted on the basis of information brought from a mobile station,which prevents an instantaneously termination and decreases of receptionlevel in a handover and makes (that results in) high qualitycommunication possible with the expansion of hardware of a base stationcontrolled.

And, since a baseband processing section is not fixed for a sector, whentraffic of one sector increases, it modulating/demodulating processingscan be assigned for some baseband processing sections. And flexibleactions are available against a failure of baseband processing sectionand others.

And, since the control of a soft handover between sectors is executedonly within a base station apparatus, it is enough to transmitinformation needed for a soft handover between only cells into aswitching equipment, which reduces the communication amount between abase station and a switching equipment and improves the communicationefficiency.

And, in the present invention, in a base station apparatus in a mobilestation system in which a service area is divided into a plurality ofcells each composed of a plurality of sectors, the base station in themobile communication has a plurality of transmitting/receiving sectionsto convert radio signals received by each sector into reception basebandsignals while converting transmission baseband signals of each sectorinto transmission radio signals, a plurality of baseband processingsections to demodulate reception signals from the reception basebandsignal while converting transmission signals into the transmissionbaseband signal, a sector switch to switch a connection between thetransmitting/receiving sections and the baseband processing sections,selection control section to select a new sector to which a handover ismade on the basis of information concerning peripheral sectorstransmitted from a mobile station and connection control section tocontrol the sector switch to connect the transmitting/receiving sectionof the new sector for a handover with the appropriate basebandprocessing section.

According to the constitution, when a handover is executed, a softhandover, in which reception signals at a plurality of sectors aremaximum ratio combined and transmission signals are transmitted via. aplurality of sectors, is achieved without expanding the hardware scaleof a base station.

And, in the present invention, there is a circuit, in which, when a softhandover between sectors is executed, a sector switch connects each oftransmitting/receiving sections of a plurality of sectors with abaseband processing section separately, demodulated signals are composedat each baseband processing section and information signals fortransmitting are distributed to each baseband processing section, whichallows to select a baseband processing section to connect when a softhandover between sectors is executed, taking into account the traffic ofsectors.

And, in the present invention, when a soft handover between sectors isexecuted, a sector switch connects transmitting/receiving sections of aplurality of sectors with the same baseband processing section and thebaseband processing section diversity composes reception signals at eachsector, which permits the maximum combination for a soft handover by onebaseband.

And, in the present invention, a baseband processing section composesreception signals obtained by side diversity between sectors, spacediversity for selecting an antenna and path diversity for selectingdelayed waves to demodulate information signals, which allows to achievehigh communication performance.

And, in the present invention, a baseband processing section convertsreception signals obtained by side diversity between sectors, spacediversity for selecting an antenna and path diversity for selectingdelayed waves into signals capable of batch processing to process bycomposing.

According to the constitution, since the results obtained by each ofpath diversity for selecting delayed waves, space diversity forselecting an antenna and side diversity between sectors, are output as acorrelation output of the same state, which allows to process thisoutput by small numbers of despreading circuits and RAKE compositecircuits.

And, in the invention, a synchronizing circuit to acquiresynchronization from reception baseband signals is preparedindependently from a baseband processing section, and the synchronizingcircuit controls the timing of processing at a plurality of basebandprocessing sections. Because of it, in the case of transmitting a largescale of data using a plurality of codes (multicode transmission), onesynchronizing circuit can collectively control the timings of aplurality of baseband processing sections and smooth and flexibledemodulation is achieved.

And, in the present invention, a spreading circuit to spread processtransmission signals using a spreading code is prepared at atransmitting/receiving section.

According to the constitution, since a signal rate passing through atransmission sector switch becomes lower, a low rate switch can be used.In addition, since a spreading circuit is prepared for a sector as aunit, the circuit is simplified rather than the case of preparing aspreading circuit at a baseband section.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating a base station apparatus in thefirst embodiment of the present invention;

FIG. 2 is a block diagram illustrating a base station apparatus in thesecond embodiment of the present invention;

FIG. 3 is a block diagram illustrating a base station apparatus in thethird embodiment of the present invention;

FIG. 4 is a block diagram illustrating a base station apparatus in thefourth embodiment of the present invention;

FIG. 5 is a block diagram illustrating a base station apparatus in thefifth embodiment of the present invention;

FIG. 6 is a block diagram illustrating a conventional base stationapparatus in a mobile communication; and

FIG. 7 is a block diagram illustrating a baseband processing section ata conventional base station apparatus in a mobile communication.

BEST MODE FOR CARRYING OUT THE INVENTION

The embodiment of the present invention is concretely described withreference to drawings in the following.

(First embodiment)

FIG. 1 illustrates a base station apparatus in the first embodiment ofthe present invention that is a base station in a mobile communicationin a CDMA system. The base station apparatus in the first embodiment ofthe present invention comprises base station transmitting/receiving unit3 to process orthogonal modulation/demodulation and frequency conversionof transmission signals and reception signals for each sector, basestation modulating/demodulating unit 5 to spread and despread with aspreading code, and to compose and separate corresponding totransmission signals and reception signals of each channel, sectorswitch 4 to select a connection between base stationmodulating/demodulating unit 5 and base station transmitting/receivingunit 3 and control section (not shown) to control operations of eachunit at the base station apparatus.

The number of existing base station transmitting/receiving unit 3 is thesame as that of sectors. The number of sectors are determined by servicecontents, the number of users and others. Base stationtransmitting/receiving unit 3 comprises a plurality of antennas 1 and 2(in this case, the number of antennas is two, however the number ofantennas is determined by the apparatus scale and others) , transmissionRF circuit 12 to process orthogonal modulation and frequency conversionof transmission signals, transmission amplifying circuit 13 to amplifytransmission radio signals, common circuit 22 to use antenna 2 in commonof transmission and reception, reception amplifying circuit 14 and 15 toamplify signals received by antenna 1 and 2, and reception RF circuit 16and 17 to process orthogonal modulation and frequency conversion ofreception signals.

And, base station modulating/demodulating unit 5 comprises N numbers ofbaseband processing (BB) section 6 to spread and despread with aspreading code of each channel and a plurality of soft handoverinterface (SHO-IF) section 7 to compose and separate signals of eachchannel.

BB section 6 comprises coding circuit 10 to code transmission signals,spreading circuit 11 to spread the transmission signals using aspreading code of a channel assigned for transmission signals,despreading circuit 18 to detect correlation of reception signals usinga spreading code of a channel assigned for reception signals,synchronization/timing control circuit 19 to control the timing of basestation apparatus by detecting a synchronization from reception signals,RAKE circuit 20 to compose each multi-pass propagated reception signalsand decoding circuit 21 to decode reception signals.

And SHO-IF section 7 comprises cell framer circuit 8 to frame anddeframe ATM cells in which information is communicated with switchingequipment in mobile system and SHO composing/distributing circuit 9 toexecute a soft handover when a handover between sectors is made.

This base station apparatus operates in an ordinary time as follows. Theordinary time means when a soft handover is not executed.

When a communication starts or a handover between cells is executed, abase station control section assigns the combination of BB section 6 andSHO-IF section 7 to base station transmitting/receiving unit 3.

Transmission data for a certain mobile station is transmitted in ATMcells from the switching equipment and provided into cell framer circuit8 at base station modulating/demodulating unit 5, where ATM cells aredeframed to extract information signals. The information signals arepassed though SHO composing/distributing circuit 9, coded at codingcircuit 10 at BB circuit 6 then framed. Information signals in framesare spreading processed at spreading circuit 11 using a spreading codeof a mobile station to output into sector switch 4.

Sector switch 4 selects a sector to transmit by a control signal of thebase station control section then outputs transmission signals intotransmission RF circuit 12 at base station transmitting/receiving unit 3of the selected sector.

Spread signals for each user are multiplied at transmission RF circuit12, processed D/A conversion, orthogonal modulation and frequencyconversion, amplified transmission amplifying circuit 13 thentransmitted for radio propagation paths from antenna 2.

On the other hand, multiplied signals transmitted via radio multipropagation paths are received by antenna 1 and 2, and amplified atamplifying circuit 14 and 15 respectively for antenna 1 and antenna 2.Reception RF signal circuit 16 and 17 execute frequency conversion, autogain control processing, demodulation processing and A/D conversion(sampling rate=k/T, 1/T=chip rate, k: positive integer number) ofreception signals respectively received by antenna 1 and 2 to outputinto sector switch 4.

Sector switch 4 selects BB section 6 (the number n of BB section) sameas when transmitted by a control signal of base station control sectionto output reception signals.

Despreading circuit 18 at the number n of BB section detects correlationof each reception signals of antenna 1 and 2 using a spreading code of amobile station. And synchronization/timing circuit 19 selects thetimings of some samples of delayed waves having high reception levelfrom each reception signals received by antenna 1 and 2. RAKE circuit 20demodulates each of selected delayed waves separately to Rake compose.Decoding circuit 21 decodes using the composed data to obtaininformation signals.

Decoded information signals are passed through SHOcomposing/distributing circuit 9, framed in ATM cells at cell framercircuit 8 then transmitted into the switching equipment.

Next, operations in a soft handover are explained.

The number of sectors for a soft handover are determined by requiredquality and apparatus scale. In this case, it is explained that a softhandover is executed between two sectors.

A base station control section decides a new sector of the number m fora handover on the basis of information concerning peripheral sectors andcells transmitted from a mobile station (reception power, interferencepower, error rate, etc.) and decides BB section 6 (the number j of BBsection) to connect the sector, taking into account the traffic.

Sector switch 4 provides output signals of reception RF circuit 16 and17 of the sector in an initial communication (referred as the firstsector) by a control signal from a base station control section andprovides output signals of reception RF circuit 16 and 17 of the numberm of sector decided to hand over into the number j of BB section 6 whichexecutes a soft handover.

Despreading circuit 18 of each BB section 6 detects correlation of eachreception signals of antenna 1 and 2 using a spreading code of a mobilestation. And synchronization/timing control circuit 19 selects thetimings of some samples of delayed waves having high reception levelfrom reception signals received by antenna 1 and 2. RAKE composingcircuit 20 demodulates each of selected delayed waves separately to Rakecompose. Decoding circuit 21 decodes using the composed data to obtaininformation signals.

Information signals decoded at the number n and number j of BB sections6 are input into SHO composing/distributing circuit 9 of SHO-IF section7 initially selected. A base station control section instructs thisSHO-IF section 7 the maximum ratio combine the signal decoded for eachsector on the basis of reliability information (reception power,interference power, error rate, etc.) transmitted from a mobile station.The composed signals are framed into ATM cells at cell framer circuit 8to transmit into the switching equipment.

On the other hand, transmission data for a mobile station is transmittedin ATM cells from the switching equipment and cell framer circuit 8deframes the cells to extract information signals. SHOdistributing/composing circuit 9 distributes the information signals tothe number n and j of BB section 6 to output.

Coding circuit 10 of each BB circuit 6 codes the information signals andframes them to output into spreading circuit 11. Spreading circuit 11spreading processes the signals using a spreading code of a mobilestation and outputs the processed signals into sector switch 4.

Sector switch 4 distributes the spreading signals to first sector andthe number m of sectors.

Transmission RF circuit 12 of base station transmitting/receiving unit 3at each sector multiplies the spread signals then processes orthogonalmodulation and frequency conversion. The converted signals are amplifiedat transmission amplifying circuit 13 then transmitted for radiopropagation paths from antenna 2.

According to the first embodiment, since an new sector for a handover isdecided on the basis of information concerning peripheral sectors andcells transmitted from a mobile station into a base station apparatus(reception level, interference power, error rate, etc.), it is notnecessary for a base station to compare reception level of a mobilestation at each sector, which simplifies circuits.

And, BB section 6 is not fixed for a sector but assigns for a sectordecided corresponding to traffics. According to the flexibleconstitution, it is possible to further reduce the hardware scale of abase station apparatus.

And in this base station, because a soft handover is executed, a shortbreak does not caouse in a soft handover between sectors. At this time,since a plurality of sectors transmit transmission signals, a softhandover is possible in a mobile station, which improves communicationquality.

And, all controls of a handover between sectors are executed at a basestation and it is enough to transmit necessary information to to aswitching equipment only when a soft handover between cells is executed,is transmitted from a base station.

(The second embodiment)

A base station apparatus in the second embodiment executes processingfor a soft handover using one baseband section.

FIG. 2 illustrates a block diagram of a base station in the secondembodiment. In the base station apparatus, each of N numbers of BBsection 36 of base station modulating/demodulating unit 35 comprisescell framer circuit 37 to frame and deframe ATM cells in whichinformation is communicated with a switching equipment, coding circuit38 to code transmission signals, spreading circuit 39 to spreadingprocess transmission signals using a spreading code of a mobile station,a plurality of despreading circuit 46 and 47 to detect correlation ofreception signals using a spreading code of a mobile station,synchronization/timing circuit 48 to control the timing of base stationapparatus by detecting a synchronization from reception signals, aplurality of RAKE circuit 49 and 50 to compose each of multi-passpropagated reception signals, timing arranging/composing circuit 51 tomaximum ratio combine outputs from each of RAKE circuit 49 and 50 anddecoding circuit 52 to decode reception signals on the basis of outputsfrom timing arranging/composing circuit 51.

The configurations of base station transmitting/receiving circuit 33 andsector switch 34 are the same as those of the first embodiment (FIG. 1)with base station control section comprised (not illustrated).

This base station apparatus operates in an ordinary time (when a softhandover is not executed) as follows.

When a communication starts or a soft handover is executed, a basestation control section decides the combination of BB section 36 andbase station transmitting/receiving unit 33.

Transmission data for a certain mobile station is transmitted in ATMcells from the switching equipment and provided into cell framer circuit37 at BB section 36, where ATM signals are deframed to extractinformation signals. The information signals are coded at coding circuit38, framed, spreading processed at spreading circuit 39 using aspreading code of a mobile station then output into sector switch 34.

Sector switch 34 selects a sector to transmit by an instruction of thebase station control section then outputs transmission signals intotransmission RF circuit 40 at base station transmitting/receiving unit45 of the selected sector.

Despread signals for each user are multiplied at transmission RF circuit40, processed D/A conversion, orthogonal modulation and frequencyconversion, amplified at transmission amplifying circuit 13 thentransmitted for radio propagation paths from antenna 32.

On the other hand, multiplied signals transmitted via radio multipropagation paths are received by antenna 31 and 32, and amplified atamplifying circuit 42 and 45 respectively for antenna 31 and 32.Reception RF signal circuit 44 and 45 execute frequency conversion, autogain control processing, demodulation processing and A/D conversion ofeach reception signals received by antenna 31 and 32 to output intosector switch 34.

Sector switch 34 selects BB section 6 (the number n of BB section) sameas when transmitted to output reception signals.

Despreading circuit 46 and 47 at BB section 36 detect correlation ofeach reception signals of antenna 31 and 32 using a spreading code. And,synchronization/timing control circuit 48 selects the timings of somesamples of delayed waves having high reception level from each receptionsignals received by antenna 31 and 32. RAKE circuit 49 and 50 demodulateeach of delayed waves selected from each reception signals received byantenna 31 and 32 separately to RAKE compose.

Timing arranging/composing circuit 51 is excute the maximum ratiocombine each output of RAKE circuit 48 and 50. The composed signals areoutput into decoding circuit 52. Decoding circuit 52 decodes using thecomposed data to obtain information signals.

Decoded information signals are framed in ATM cells at cell framercircuit 37 then transmitted into the switching equipment.

Next, operations in a soft handover are explained. In this case, it isexplained that a soft handover is executed between two sectors.

A base station control section decides a sector to hand over (referredas a new sector )on the basis of information concerning peripheralsectors and cells transmitted from a mobile station (reception power,interference power, error rate, etc). Based on the decision, sectorswitch 34 provides output signals of reception RF circuit 44 and 45 ofthe sector in the initial communication (referred as an old sector) andoutput signals of reception RF circuit of the new sector into the sameBB section 6 of the number n.

Since synchronization/timing control circuit 48 at BB section 36 alreadyacquired the synchronization with the signals from the old sector, ittries to acquire a synchronization with signals from the new sector.When the synchronization is acquired, despreading circuit 46 detectscorrelation of reception signals from the old sector using a spreadingcode, and despreading circuit 47 detects correlation of receptionsignals from the new sector using a spreading code.

RAKE circuit 49 demodulates each of delayed waves of a timing selectedat synchronization/timing circuit 48 from outputs at despreading circuit46 separately to RAKE compose. And, RAKE circuit 50 demodulates each ofdelayed waves of a timing selected at synchronization/timing circuit 48from outputs at despreading circuit 47 separately to RAKE compose.

Timing arranging/composing circuit 51 is execute the maximum ratiocombine outputs of each RAKE circuit 49 and 50, and arranging shifts oftiming between sectors.

Decoding circuit 52 decodes using the composed signals to obtaininformation signals. Decoded information signals are framed into ATMcells at cell framer circuit 37 then transmitted into the switchingequipment.

On the other hand, transmission data for the mobile station istransmitted from the switching equipment in ATM cells. And onlyinformation signals are extracted at cell framer circuit 37, coded atcoding circuit 38, spreading processed at spreading circuit 39 using aspreading code to assigned the mobile station then the processed signalsare output into sector switch 34.

Sector switch 34 assigns the same spread signals for the old sector andthe new sector.

Transmission RF circuit 40 of base station transmitting/receiving unit33 at each sector multiplies spread signals and processes orthogonalconversion and frequency conversion of the signals. Converted signalsare amplified at transmission amplifying circuit 41 then transmitted forradio propagation paths from antenna 32.

And, in a soft handover between cells, information signals decoded atdecoding circuit 52 and reliability information (reception level, etc.)are framed into ATM cells and transmitted into the switching equipment.The switching equipment composes or selects information signals receivedfrom an old sector and an new sector using this reliability informationto obtain desired information signals.

According to the second embodiment, in a soft handover between sectors,since reception signals from an old sector and a new sector are executedthe maximum ratio combine by diversity using the same baseband section,the effectiveness to improve communication quality can be acquired.

And, a soft handover bewteen sectors is controlled within a base stationand it is enough to transmit necessary information to a switchingequipment only when a soft handover between cells is executed. Thatreduces the communication amount between a base station and a switchingequipment, which improves the communication efficiency.

(Third embodiment)

The circuit scale of a base station in the third embodiment can bereduced compared to that in the second embodiment.

FIG. 3 illustrates a block diagram of a base station in the thirdembodiment. In the base station apparatus, each of N numbers of BBsection 66 of base station modulating/demodulating unit 65 comprisescell framer circuit 67 to frame and deframe ATM cells in whichinformation is communicated with a switching equipment, coding circuit68 to code transmission signals, spreading circuit 69 to spreadingprocess transmission signals using a spreading code of a mobile station,synchronization/timing control circuit 76 to control the timing of basestation apparatus by detecting a synchronization from reception signals,path selecting circuit 77 to select a delayed wave of high receptionlevel, despreading/timing arranging circuits 78 to detect correlation ofreception signals of the selected path using a spreading code of amobile station, RAKE circuits 79 to compose reception signals of eachselected path, and decoding circuit 80 to decode reception signals onthe basis of outputs from RAKE circuits 79.

The configurations of base station transmitting/receiving circuit 63 andsector switch 64 are the same as those of the first embodiment with abase station control section comprised, however it is not illustrated.

In the base station apparatus, transmission in an ordinary time (withoutsoft handover) is executed in the same way as the second embodiment.

On the other hand, multiplied signals transmitted via radio multipropagation paths are received by antenna 61 and 62, and respectivelyamplified at reception amplifying circuit 72 and 73. Reception RF signalcircuit 74 and 75 executes frequency conversion, AGC processing,demodulation processing and A/D conversion of each reception signalsreceived by antenna 61 and 62 to output into sector switch 64.

Sector switch 64 selects BB section 66 same as when transmitted tooutput reception signals.

Synchronization/timing control circuit 76 at BB section 66 selects thetimings of some samples of delayed waves having high reception levelfrom reception signals received by each antenna 61 and 62 then outputs apath selection signal into path selecting circuit 77. Path selectingcircuit 77 selects output signals from sector switch 64 by the pathselection signal and outputs some samples of delayed waves having highreception level into despreading/timing arranging circuit 78.Despreading/timing arranging circuit 78 detects correlation of theoutput signals using a spreading code. RAKE circuit 79 demodulates eachof selected delayed waves separately to Rake compose.

The output signals from RAKE circuit 79 are provided into decodingcircuit 80 and decoding circuit 80 decodes the signals to obtaininformation signals.

Decoded information signals are framed in ATM cells at cell framercircuit 8 then transmitted into the switching equipment.

When a soft handover is executed, in the same way as the secondembodiment, sector switch 64 provides outputs from reception RF circuit74 and 75 of a sector in an initial communication (old sector) andreception RF circuit of a new sector into the same BB section 66 ofnumber 66.

Since synchronization/timing control circuit 76 at BB section 66 alreadyacquired the synchronization with the signals from the old sector, ittries to acquire the synchronization with the signals from the newsector. When the synchronization is established, synchronization/timingcontrol circuit 76 selects some samples of delayed waves having highreception then outputs a path selection signal into path selectingcircuit 77. Path selecting circuit 77 selects output signals from sectorswitch 64 by the path selection signal and outputs some samples ofdelayed waves having high reception level into despreading/timingarranging circuit 78. Despreading/timing arranging circuit 78 detectscorrelation of the output signals with a spreading code arranging thetiming of shifts between sectors. RAKE composing circuit 79 demodulateseach of selected delayed waves separately to Rake compose. The outputsignals from RAKE composing circuit 79 are provided into decodingcircuit 80 and decoding circuit 80 decodes the signals to obtaininformation signals. Decoded information signals are framed in ATM cellsat cell framer circuit 8 then transmitted into a switching equipment.

The processing of transmission signals in a soft handover is executed inthe same way as the second embodiment.

And, when a soft handover between cells is executed, information signalsdecoded at decoding circuit 80 and reliability information (receptionlevel, etc.) are framed into ATM cells and transmitted into theswitching equipment. The switching equipment composes or selectsinformation signals received from an old sector and a new sector usingthe reliability information to obtain desired information.

As described above, when a soft handover between cells is executed, thebase station apparatus executes the maximum ratio combine for receptionsignals from the old sector and the new sector using the same basebandsection. At this time, path diversity to select a delayed wave, spacediversity to select an antenna and site diversity between sectors areexecuted by processing correlation outputs from despreading/timingarranging circuit 78 at the same state. For instance, by selecting fourdelayed waves (in the case where the number of tap is four) from twostates of delayed wave interval and antenna, and sector space, thencomposing correlation outputs from despreading/timing arranging circuit78, these diversities are achieved. Because of it, high performancecommunication is achieved without having the large number ofdespreading/timing arranging circuit 78 and RAKE composing circuit 79.

And, since a soft handover is controlled within a base station, as wellas the first embodiment and the second embodiment, the communicationefficiency between the base station and the switching equipment can beimproved.

(Fourth embodiment)

A base station of the fourth embodiment allows to batch control thetimings of operations of each BB section.

FIG. 4 illustrates a block diagram of abase station apparatus of thefourth embodiment. This base station apparatus has the constitutionwhere synchronization/timing control circuit 106, which is used to be atBB section, is prepared independently and the timing control at BBsection 96 is executed by timing switch 107. Other constitutions are thesame as those of the third embodiment.

This synchronization/timing control circuit 106 outputs a timing signalby detecting a synchronization from reception signals, and this timingsignal is output into timing switch 107 then distributed to each BBsection 96.

In transmitting ordinary data, synchronization/timing control circuit106, in the same way as the third embodiment, outputs a path selectingsignal by selecting the timings of some samples of delayed waves havinghigh reception level. This path selecting signal is provided intocorresponding BB section 96 then BB section 96 executes operations oftransmission and reception, and soft handover in the same way as thethird embodiment.

And, in the case of high speed data transmitting data such as movingpictures and others, the transmission using a plurality of codes(channels) is executed. In such case, one synchronization/timing controlcircuit 106 is connected with a plurality of BB section 96 throughtiming switch 107 and batch controls the operating timings of each BBsection 96.

As described above, in this base station, since a synchronizing sectionis prepared independently, the timing control in the case of using aplurality of codes can be batch controlled, which allows smoothexecution of high speed data communication using a plurality of codesconcurrently.

(Fifth embodiment)

In a base station of the fifth embodiment, a spreading section tospreading process coded transmission signals is prepared at a basestation transmitting/receiving unit, a sector switch is divided into atransmission sector switch and a reception sector switch, and signalspassed through a transmission sector switch becomes a basebandfrequency.

FIG. 5 illustrates a block diagram of a base station apparatus of thefifth embodiment. In this base station, a spreading circuit, which isprovided in BB section 236 of the base station of the first embodiment,is prepared at base station transmitting/receiving unit 233, andtransmission signals, which are coded then framed at coding circuit 211at BB section 236, are input into spreading circuit 212 at base stationtransmitting/receiving unit 233 through transmission sector switch 235.Reception signals are input into despreading circuit 219 at BB section236 from base station transmitting/receiving unit 233 through receptionsector switch 234.

Spreading circuit 212 is a processing section to spread transmissionsignals into a wide frequency band by modulating coded transmission datawith a spreading code. As a spreading code, there are a short codeassigned for all users to identify each user and a long code assignedfor all sectors to identify each sector. A short code is a code having ashort period such as 64 and a long code is a code having a very longperiod such as about ten thousands.

It is assumed that output signals from coding circuit 211 is a 64 kbpsbaseband signal of spreading ratio 64. First, the baseband signal ofeach user is converted into a signal of 4.096 Mcps (Mega chips persecond) that is 64 times bigger than the original speed by multiplying ashort code of spreading ratio 64 by each bit period of the basebandsignal. The signal of each user is added then the resultant signals aremultiplied by a long code assigned for a sector to generate transmissiondata of the sector. Since the multiplying of a long code is executedwith the same chip rate as the short code, the chip rate of the outputsignals is still 4.096 Mcps after multiplying a long code.

When spreading processing is executed at base stationtransmitting/receiving unit 233 not at BB section 236, spreadingprocessing per sector not per user is executed. Spreading circuit 212 ofeach sector comprises short code multiplying circuits of the numbercorresponding to the number of short codes that are available in onesector, an adding circuit and a long code multiplying circuit. Eachtransmission frames input from BB section 236 though transmission sectorswitch 235 is input into a corresponding short code multiplying circuitto multiple. By adding these multiplied results then multiplying a longcode at a long code multiplying circuit, spreading processing per sectoris executed.

According to described above, the number of long code multiplyingcircuits, which used to require the number of circuits of BB section236, is reduced into the number of sectors. And, since the number ofshort code multiplying circuits is the same, it is possible to decreasethe number of circuits and reduce the speed of signals passing throughtransmission sector switch.

In transmission signals from a mobile station, since despreadingprocessing per user is executed in the same way as the first embodiment,the rate of signals passing through reception sector switch 234 is thesame as the chip rate before despreading. Accordingly, into transmissionsector switch 235 for low rate and reception sector switch for high rate234 are prepared separately as a sector switch. Other constitutions arethe same as those of the first embodiment.

This base station apparatus 233 operates in an ordinary time (when asoft handover is not executed) as follows.

Transmission data for a certain mobile station is transmitted in ATMcells from a switching equipment and provided into cell framer circuit210 at base station modulating/demodulating unit 237, where ATM cellsare deframed to extract information signals. The information signals arepassed though SHO distributing/composing circuit 239, coded at codingcircuit 211 at BB circuit 236, framed then output into transmissionsector switch 235.

Transmission sector switch 235 selects a sector to transmit by a controlsignal of a base station control section (not illustrated) then outputstransmission signals into spreading circuit 212 at base stationtransmitting/receiving unit 233 of the selected sector. Spreadingcircuit 212 executes spreading processing by multiplying transmissionframes transmitted from a plurality of BB section 236 throughtransmission sector switch 235 by a short code, adding the results andmultiplying it with a long code. Transmission signal frames spreadingprocessed are output into transmission RF circuit 213, processed D/Aconversion, orthogonal modulation and frequency conversion attransmission RF circuit 213, amplified at transmission amplifyingcircuit 214 then transmitted for radio propagation paths from antenna 2.

On the other hand, multiplied signals transmitted via. radio multipropagation paths from a plurality of base stations are received byantenna 231 and 232, and amplified at reception amplifying circuit 215and 216 respectively for antenna 231 and 232. Reception RF circuit 217and 218 execute frequency conversion, AGC processing, demodulationprocessing and A/D conversion of reception signals received by antenna231 and 232 respectively to output into sector switch 234.

Reception sector switch 234 selects BB section 236 (the number n of BBsection) same as when transmitted by a control signal of base stationcontrol section to output reception signals. Following processing ofreception signals is executed in the same way as the first embodiment.

Next, operations in a soft handover are explained.

A base station control section decides the number m of sector to handover on the basis of information concerning peripheral sectors and cellstransmitted from a mobile station (reception power, interference power,error rate, etc.) and decides BB section 236 (the number j of BB section236) to connect the sector, taking into account the traffic.

Reception sector switch 234 provides output signals of reception RFcircuit 217 and 218 of the sector in an initial communication (referredas the first sector) to the number n of BB section 236 in the initialcommunication, and provides output signals of reception RF circuit 217and 218 of the number m of sector decided to hand over into the number jof BB section 236 which executes a soft handover. Following processingof reception signals is executed in the same way as the firstembodiment.

On the other hand, transmission data for a mobile station is transmittedin ATM cells from a switching equipment and cell framer circuit 210deframes the cells to extract information signals. SHOdistributing/composing circuit 210 distributes the information signalsto the number n and j of BB section 236 to output.

Coding circuit 211 of each BB circuit 236 codes the information signalsand frames to output into transmission sector switch 235. Transmissionsector switch 235 distributes transmission frames to the first sectorand the number m of sector.

Spreading circuit 212 of base station transmitting/receiving unit 233 ateach sector spreading processes transmission frames to output intotransmission RF circuit 213. Transmission RF circuit 213 processesorthogonal modulation and frequency conversion of spread signals. Theconverted signals are amplified at transmission amplifying circuit 214then transmitted for radio propagation paths from antenna 232.

The case, where spreading circuit 212 is prepared at base stationtransmitting/receiving unit 233 and, as a sector switch, transmissionsector switch 235 and reception sector switch 234 are prepared, isexplained in the base station apparatus of the transformed firstembodiment. However, it is obvious that the similar transformation canbe applied for base stations of the second embodiment through fourthembodiment. It is also obvious that, in operations of those basestations, operations in the case of transmission and a handover are thesame as those of the fifth embodiment, and reception operations are thesame as those of the second embodiment though the fourth embodiment.

Accordingly, in the case of preparing spreading circuit 212 at basestation transmitting/receiving unit 233 and preparing reception sectorswitch 235 and reception sector switch as a sector switch in basestation apparatus of the second embodiment through the fourthembodiment, a low rate switch is available for a transmission sectorswitch, which allows to decrease the circuit scale of spreading circuit.

Industrial Applicability

As described above, the base station apparatus in a mobile communicationin the present invention is useful in a soft handover between sectors ina base station apparatus for sector transmitting and receiving in acellular system. And it is appropriate for reducing the hardware scaleof a base station apparatus and improving the communication quality.

What is claimed is:
 1. A base station apparatus in a mobilecommunication system in which a service area is divided into a pluralityof cells each composed of a plurality of sectors, said base stationapparatus comprises:a plurality of transmitting/receiving sections eachfor converting a radio signal received at each sector into a receptionbaseband signal, while converting a transmission baseband signal of eachsector into a transmission radio signal; a plurality of basebandprocessing sections each for demodulating a reception signal from saidreception baseband signal, while converting a transmission signal intosaid transmission baseband signal; sector switch means for switching aconnection between said transmitting/receiving sections and saidbaseband processing sections; selecting means for selecting a new sectorfor a handover on the basis of information concerning peripheral sectorstransmitted from a mobile station; and connection control means forcontrolling said sector switch means to connect thetransmitting/receiving section of said new sector for a handover withsaid baseband processing section appropriate for saidtransmitting/receiving section.
 2. The base station apparatus in themobile communication system according to claim 1, wherein saidconnection control means, while maintaining a connection between saidtransmitting/receiving section of an old sector for a handover and saidbaseband processing section when a soft handover between sectors isexecuted, controls to connect the transmitting/receiving section of saidnew sector for a handover with said baseband processing section.
 3. Thebase station apparatus in the mobile communication system according toclaim 1 further comprise:means for composing, when a soft handoverbetween sectors is executed, each reception signal demodulated at eachof said baseband processing sections connected with respectivetransmitting/receiving sections of the old sector and the new sector;and means for distributing the transmission signal for said eachbaseband processing section connected with respectivetransmitting/receiving sections of the old sector and the new sector. 4.The base station apparatus in the mobile communication system accordingto claim 1, whereinsaid connection control means controls said sectorswitch to connect the transmitting/receiving sections of the old sectorand new sector with the same baseband processing section at a receptiontime while a soft handover between sectors is executed, and saidbaseband processing section diversity composes reception basebandsignals output from said transmitting/receiving sections.
 5. The basestation apparatus in the mobile communication system according to claim4, wherein said baseband processing section demodulates a receptionsignal by composing signals obtained by site diversity between sectors,space diversity to select an antenna and path diversity to select adelayed wave.
 6. The base station apparatus in the mobile communicationsystem according to claim 5, wherein said baseband processing sectionconverts signals obtained by site diversity between sectors, spacediversity to select an antenna and path diversity to select a delayedwave into a signal capable of being batch processed to process bycomposing.
 7. The base station apparatus in the mobile communicationsystem according to claim 1, wherein said base station apparatuscomprises synchronizing means for acquiring a synchronization of saideach baseband processing sections from said reception baseband signalprovided into said each baseband processing section, and batch controlsa processing timing at said each baseband processing section.
 8. Thebase station apparatus in the mobile communication system according toclaim 1, wherein said transmitting/receiving section comprises spreadingmeans for spreading a transmission signal using a spreading code.
 9. Thebase station apparatus in the mobile communication system according toclaim 8, wherein said transmitting/receiving section comprises atransmitting circuit having said spreading means for converting saidtransmission baseband signal into said transmission radio signal and areceiving circuit to convert said received radio signal into saidreception baseband signal, and said sector switch means comprises atransmission sector switch to input said transmission baseband signaloutput from said baseband processing section into said transmittingcircuit of a sector corresponding to an instruction by said connectioncontrol means, and a reception sector switch to input said receptionbaseband signal output from a receiving circuit of said sector into saidbaseband processing section corresponding to an instruction by saidconnection control means.
 10. The base station apparatus in the mobilecommunication system according to claim 1, wherein said selecting meansis characterized in that the information concerning peripheral sectorsincludes at least either one of reception power of a peripheral sector,interference power and error rate.
 11. The base station apparatus in themobile communication system according to claim 1, wherein saidconnection control means is characterized to select the basebandprocessing section appropriate to connect the new sector for a handover,taking into account traffic of a sector.
 12. A soft handover methodbetween sectors in a base station apparatus in a mobile communicationsystem, wherein said base station apparatus comprises atransmitting/receiving section for each sector, a baseband processingsection for each sector and a sector switch to select a connection withsaid transmitting/receiving section and said baseband processingsection,said soft handover method between sectors, wherein a softhandover between sectors is executed by selecting a plurality of sectorson the basis of information concerning peripheral sectors obtained froma mobile station, connecting transmitting/receiving sections of aplurality of sectors selected and corresponding baseband processingsection with the sector switch to ensure a plurality of channels withsaid mobile station.